This invention relates to improved vacuum cleaners having devices for cleaning accumulated dust from the surface of a filter bag in the cleaner.
After a conventional industrial or commercial vacuum cleaner of the type utilizing a filter bag has been in use for a period of time, dust filtered from the air stream tends to accumulate on the surface of the filter bag and restrict the flow of air through the bag. As a result, the suction produced by the cleaner is reduced, and its overall cleaning effectiveness is adversely affected. Various expedients have been proposed in the past for overcoming this effect, but none to my knowledge has enjoyed sufficient acceptance to warrant its use on a substantial scale in actual production cleaners.
One prior patent showing devices for this purpose in U.S. Pat. No. 3,236,032, which discloses arrangements having rotatable brushes or other rotors mounted within a cleaner bag and acting upon rotation to contact the inner surface of the bag and dislodge accumulated dust from its outer surface. However, these rotors of U.S. Pat. No. 3,236,032 are rendered accessible for actuation only when a top cover of the cleaner is removed. Such removal of the cover exposes a handle within the device by which the rotor may be manually turned to clean the bag, after which the cover and its carried parts must be reattached to the main lower portion of the vacuum cleaner. U.S. Pat. No. 3,621,641 shows arrangements in which a rotary part is connected to the bag eccentrically, and acts to move the bag upon rotation of the rotor in a manner displacing dust from its outer surface. U.S. Pat. No. 3,358,316 shows a cleaner in which a filter bag is mounted for what is termed a breathing movement in response to a change in vacuum conditions in the device, and this breathing movement is intended to clean dust from the bag surfaces. U.S. Pat. No. 3,276,066 shows a cleaner having a planar filter from which particles are removed by a rotary brush.